From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 1535FC71153 for ; Tue, 29 Aug 2023 15:13:44 +0000 (UTC) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (1024-bit key; unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=e8H0uIgy; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=e8H0uIgy; dkim-atps=neutral Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4RZrY33MKDz3c3p for ; Wed, 30 Aug 2023 01:13:43 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=e8H0uIgy; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=e8H0uIgy; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=redhat.com (client-ip=170.10.129.124; helo=us-smtp-delivery-124.mimecast.com; envelope-from=joe.lawrence@redhat.com; receiver=lists.ozlabs.org) Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4RZrX30gZyz2ytr for ; Wed, 30 Aug 2023 01:12:50 +1000 (AEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1693321967; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type; bh=w3CVYpgxTsvHbKTea4nnprzsRm89plHSxyih6vxlw24=; b=e8H0uIgylawxU+7re+cJ2m9NIKNvKpbrTakWjg1JnvxXm4JXkQTQqCCtesXvV3JZaKEhCN 6ccJKveNCD06z5FsOOk9hLGMlKTxnFQtPgootUsYt7FlA+uhkzC+FqLdJFtZ8a4Zs4IK7U etCd7DRXRVfRR8izm+P5kUyIJoHrH/U= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1693321967; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type; bh=w3CVYpgxTsvHbKTea4nnprzsRm89plHSxyih6vxlw24=; b=e8H0uIgylawxU+7re+cJ2m9NIKNvKpbrTakWjg1JnvxXm4JXkQTQqCCtesXvV3JZaKEhCN 6ccJKveNCD06z5FsOOk9hLGMlKTxnFQtPgootUsYt7FlA+uhkzC+FqLdJFtZ8a4Zs4IK7U etCd7DRXRVfRR8izm+P5kUyIJoHrH/U= Received: from mimecast-mx02.redhat.com (66.187.233.73 [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-277-xaklgDF5NhOHUji6ZcH9AA-1; Tue, 29 Aug 2023 11:12:44 -0400 X-MC-Unique: xaklgDF5NhOHUji6ZcH9AA-1 Received: from smtp.corp.redhat.com (int-mx10.intmail.prod.int.rdu2.redhat.com [10.11.54.10]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 0194A1C03D96; Tue, 29 Aug 2023 15:12:44 +0000 (UTC) Received: from redhat.com (unknown [10.22.16.28]) by smtp.corp.redhat.com (Postfix) with ESMTPS id BE4FD401051; Tue, 29 Aug 2023 15:12:43 +0000 (UTC) Date: Tue, 29 Aug 2023 11:12:42 -0400 From: Joe Lawrence To: linuxppc-dev@lists.ozlabs.org Subject: Recent Power changes and stack_trace_save_tsk_reliable? Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline X-Scanned-By: MIMEDefang 3.1 on 10.11.54.10 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: live-patching@vger.kernel.org, Joe Lawrence , Ryan Sullivan Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Hi ppc-dev list, We noticed that our kpatch integration tests started failing on ppc64le when targeting the upstream v6.4 kernel, and then confirmed that the in-tree livepatching kselftests similarly fail, too. From the kselftest results, it appears that livepatch transitions are no longer completing. Looking at the commit logs for v6.4, there looks to be some churn in the powerpc stack layout code -- I am suspicious that "reliable" stack unwinding may be left untested/broken after those changes. AFAICT, the livepatching subsystem is the only user of this interface in kernel/livepatch/transition.c :: klp_check_stack()'s call to stack_trace_save_tsk_reliable(). As such, the livepatching kselftests are probably the only way to test reliable unwinding. Unfortunately, git bisect isn't cooperating (we keep falling into a long span of non-bootable commits, despite efforts to `git bisect skip` over them), so we don't have an offending commit or patchset to point to. A few other details: - Test machine is a Power 9 9009-42A (IBM Power System S924) - Reproducable with v6.4, v6.5 - Minimal repro: -- Build with CONFIG_TEST_LIVEPATCH=m -- Run tools/testing/selftests/livepatch/test-livepatch.sh If this has already been report or fixed, please send any pointers to threads / commits. If not, I can provide any other info to help reproduce. Thanks, -- Joe